Stó:lō longhouses (s'iltexwáwtxw
) were massive structures that provided shelter to many people in the village. The Stó:lō longhouses had a very distinctive shed-roof design. The longhouses were built along the river's edge, with the taller wall facing the river and the shorter wall facing the village or forest behind it. Longhouses were generally built side by side along a river's edge, but were also built in rows, one behind the other, if space did not permit.

The longhouse was built using hand-split cedar planks lashed on to a frame of upright poles and crossbeams. The front of the house was generally five to six metres in height, while the back wall was four to five metres in height. The width of the building could be between six and eighteen metres, while the length of the longhouse could be twice as long (if not longer).

The longhouses were constructed by a number of specialists, but family members assisted in the process. Specialists were responsible for choosing the cedar trees that would be used for the planks of the longhouse, while other specialists designed the house posts, beams and planks for the longhouse. Once a longhouse was completed, the families had a ceremony in honour of its completion and of the people who assisted in the production.

A longhouse could contain a small number of nuclear families or house an extended family of a hundred or more people. Mats made from bulrush or cedar bark were used to divide the house in separate areas for each family. Along the walls were plank benches for sleeping, under which supplies could be stored (supplies were also suspended form the roof beams). The floor was covered with sand that was brought up from the beach. Each area in the longhouse had its own fire pit, and the smoke was allowed to escape through an opening in the roof, where individual planks were pushed aside.

The longhouses along the river, as well as the living areas in the longhouse itself, were arranged by status. The longhouses belonging to the families with the highest status had the most favorable locations along the river's edge. As well, the elders of higher status, and their families, were housed farthest from the main door of the longhouse, while those of lower status were housed nearest the main door. This was for a number of reasons, but mainly for protection of the higher status families.